JPH08104240A - Forward/backward operation switching device for work vehicle - Google Patents

Abstract

PURPOSE: To safely perform switching forward/backward operation easily while a steering lever of a work vehicle is grasped. CONSTITUTION: In a steering lever 1, a momentary push botton type forward operating push botton switch 2, neutral operating push botton switch 3 and a backward operating push button switch 4 are provided to be connected to a control device 5. This control device 5 is connected to a forward operation solenoid valve 23 of operating a forward clutch 12 and to a backward operation solenoid valve 24 of operating a backward clutch 13. Since the control device 5 has a self holding function of each push button switch and an interlocking function of placing in neutral when simultaneously pressed the two switches, steering and switching of forward/backward operation can be operated simultaneously, easily and further safely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forward / reverse switching device for a work vehicle such as a shovel loader, and more particularly to a forward / reverse switching device for a work vehicle having a steering lever provided with a forward / backward switching push button switch.

[0002]

2. Description of the Related Art Conventionally, a work vehicle such as a shovel loader generally has a steering wheel arranged in the front center of the driver's seat.
The work machine lever is located on the right side, and the shift and forward / reverse switching levers are located on the left side.The operator operates the work machine with the right hand, the steering operation with the steering wheel with the left hand, and the traveling operation for shifting / forward / reverse switching. It is carried out. Therefore, when switching between forward and backward movements during loading work, etc., the left hand must be released from the steering wheel to operate the switching lever, and this work is complicated and requires skill.

To solve this problem, Japanese Patent Laid-Open No. 4-356272 shown in FIG. 8 has been proposed as a first conventional technique. That is, in FIG. 8, a steering wheel 30 is provided in the front portion of the driver's seat, and a work machine operating lever 31 is provided on the right side thereof. A knob 32 is attached to the steering wheel 30, and a forward / backward changeover switch 33 is provided on the knob 32. The operator operates the work machine with the work machine operating lever 31 with the right hand, and the steering wheel 30 with the left hand. Further, the forward / reverse switching switch 33 allows the steering operation and the forward / reverse switching to be performed without releasing the hand from the steering wheel 30.

Further, in recent years, as a second conventional technique having a lever type steering operation device in place of a steering wheel for convenience of steering operation during work, as shown in FIG. 501021 has been proposed. In FIG. 9, a mono-lever type steering lever 40 is provided on the left side of the driver's seat, and a gear shift lever 41 is rotatably attached to the upper portion of the steering lever 40 by a shaft 42. Further, a swing switch 43 for performing forward / reverse switching operation is mounted on the back side of the steering lever 40. The speed change lever 41 can be rotated by the thumb of the left hand, and the operator operates the steering lever 4
The first, second, third, and fourth speed stages can be selected and the swing switch 43 can be operated to switch the vehicle between forward and backward without releasing the hand from 0.

Further, as a third conventional technique, in WO93 / 15927 shown in FIG. 10, a plurality of contact-type switching buttons 51 for operating the head of a mono-lever type steering lever 50 and a working machine operation. A plurality of contact-type switching buttons 52 for performing the operation are attached, and the operator operates the switching buttons 51 and 52 while traveling while keeping the steering lever 50 held, to switch between forward and backward movement and the working machine. Can be operated.

[0006]

However, in the configurations of the first and second prior arts described above, there is a problem that it is difficult to operate because the operation switch is not a push button switch. Further, the third conventional technique is a contact type switching button, but there is a safety problem because it does not have a protective function when two or more switching buttons are accidentally pressed. Further, when the contact-type switching button is released, there is no function of holding the output as it is, and there is a problem that the switching button must be continuously pressed to hold the output.

The present invention has been made in view of the above problems, and is a push button switch that is easy to operate, and has a protection function when two or more buttons are accidentally operated at the same time, and when the push button switch is released. It is an object of the present invention to provide a forward / reverse switching device for a work vehicle having the output holding function.

[0008]

In order to achieve the above object, a forward / reverse switching device for a working vehicle according to the present invention is a working vehicle having a steering lever provided with a forward / reverse switching switch for traveling, and at least the steering lever is provided in the working vehicle. Forward,
Equipped with push button switches that can be switched between neutral and reverse positions.

The forward / reverse switching device of the work vehicle includes a control circuit for receiving a signal from each push button switch to excite a solenoid valve for feeding oil to each forward / reverse clutch of the work vehicle. Connect each pushbutton switch, relay, relay contact or diode in series between both terminals of the control power supply as shown below. (1) Forward operation push button switch and first relay F1 (2) Neutral operation push button switch and second relay N1 (3) Reverse operation push button switch and third relay R1 (4) First relay F1 A contact and B of the second relay N1
From the series connection of the contact and the B contact of the third relay R1 and the fourth relay F2, and the series connection of the A contact of the first relay F1, the B contact of the second relay N1 and the B contact of the third relay R1 to the diode. The first relay F1 is electrically connected via the. (5) Series connection of B contact of first relay F1 and B contact of third relay R1 and second relay N1 (6) B contact of first relay F1, B contact of second relay N1 and third relay R1 Connection with the A contact of the fifth relay R2, and the B contact of the first relay F1 with the second relay N1
The B contact and the A contact of the third relay R1 are connected in series so as to energize the third relay R1 via the diode. (7) A contact of fourth relay F2 and forward solenoid (8) A contact of fifth relay R2 and reverse solenoid

Further, the forward / reverse switching device for the work vehicle is
A control circuit for exciting a solenoid valve for feeding oil to each clutch of the work vehicle in response to a signal from each push button switch is provided, and each push button switch is provided between both terminals of the control power supply in this control circuit. Connect relays, relay contacts or diodes in series as shown below. (1) Forward operation push button switch and first relay F1 (2) Neutral operation push button switch and second relay N1 (3) Reverse operation push button switch and third relay R1 (4) First relay F1 A contact and B of the second relay N1
A series connection between the contact and the B contact of the third relay R1 and the forward solenoid, and a series connection between the A contact of the first relay F1, the B contact of the second relay N1 and the B contact of the third relay R1 via the diode. The first relay F1 is connected so as to be energized. (5) Series connection of B contact of first relay F1 and B contact of third relay R1 and second relay N1 (6) B contact of first relay F1, B contact of second relay N1 and third relay R1 Series connection with the A contact of the first relay F1 and the reverse solenoid, and the B contact of the first relay F1 and the second relay N1
The B contact and the A contact of the third relay R1 are connected in series so as to energize the third relay R1 via the diode.

[0011]

As described above, since the forward / reverse switching device of the work vehicle is equipped with the push button switches capable of switching the steering lever to at least three positions of forward, neutral and reverse, the steering operation is performed by gripping the steering lever. It is possible to perform forward and backward and neutral operations while performing.
Therefore, the steering operation by the operator is extremely easy. The self-holding function of each push-button switch does not require the push-button switch to be continuously pressed because the output is held even if the push-button switch is pressed once and then released. Further, when two or more push button switches are simultaneously operated or reset, the push button switches always become neutral, and a plurality of operations are not performed at the same time, so that the driving operation can be performed safely.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a forward / reverse switching device for a work vehicle according to the present invention will be described in detail below with reference to the drawings. FIG.
FIG. 3 is an overall control circuit diagram of a forward / reverse switching device. A forward switch 2, a neutral switch 3 and a reverse switch 4, which are momentary type push button switches, are mounted on the upper portion of the steering monolever 1 provided on the front side and the left side of the driver's seat. These push button switches and control device 5 are provided. And are electrically connected to. A work machine operating lever 6 is provided in front of the driver's seat and on the right side.

A traveling device 1 driven by an engine 10.
1, a forward clutch 12 and a reverse clutch 13 are provided. The forward clutch 12 is turned on and the reverse clutch 1
When 3 is turned off, the power passes through the forward reduction gear 14 and causes the output shaft 16 to rotate forward. Forward clutch 12 OF
F, when the reverse clutch 13 is turned ON, the power passes through the reverse reduction gear 15 and rotates the output shaft 16 in reverse.

A forward solenoid valve 22 and a reverse solenoid valve 24 are provided in the discharge circuit 21 of the hydraulic pump 20, and the forward solenoid 23 and the reverse solenoid 25 are connected to the control device 5. When the forward switch 2 of the steering monolever 1 is pressed, the forward solenoid 23 is excited via the control device 5 and the forward solenoid valve 22 is switched to the low position as shown in FIG. Since it is supplied to a cylinder (not shown) of the forward clutch 12, the forward clutch 12 is turned on.
N, the output shaft 16 rotates forward. When the reverse switch 4 is pressed, the reverse solenoid valve 2 is pressed as shown in FIG.
4 is switched to the b position and the pressure oil is supplied to the circuit 27 and is supplied to the cylinder (not shown) of the reverse clutch 13, so that the reverse clutch 13 is turned on and the output shaft 16 rotates in the reverse direction. When the neutral switch 3 is pressed, both the forward solenoid 23 and the reverse solenoid 25 are turned off and the forward solenoid valve 22 and the reverse solenoid valve 24 are both in the a position as shown in FIG. Since pressure oil is not supplied to both the cylinder and the cylinder (not shown) of the reverse clutch 13, the forward clutch 12 and the reverse clutch 1
3 is turned off, and the output shaft 16 is in a non-driving state.

FIG. 2 is a circuit diagram of a forward / reverse switching control circuit showing a first embodiment of the control device 5, that is, a main switch 7
And the battery 8 form a power supply circuit. The forward / reverse switching device for the work vehicle receives the signals from the respective push button switches, and the forward / reverse clutches 12, 13 of the work vehicle are received.
Is provided with a control circuit for exciting the solenoids 23, 25 of the solenoid valves 22, 23 for feeding oil to a cylinder (not shown), and the push button switches 2, 3 are provided between both terminals of the control power supply 8 in the control circuit. , 4, relays F1, F
2, N1, R1, R2, relay contacts F1A, F1B, F
2A, N1B, R1A, R1B, R2A or diodes 17, 18 are respectively connected in series as follows. (1) Push button switch 2 for forward operation and first relay F
1 (2) Pushbutton switch 3 for neutral operation and second relay N
1 (3) Push-button switch 4 for reverse operation and third relay R
1 (4) A contact F1A of the first relay F1 and the second relay N
1 B contact N1B and B relay R1B of the third relay R1 are connected in series and a fourth relay F2, and A contact F1A of the first relay F1, B contact N1B of the second relay N1 and B of the third relay R1. Diode 1 from the series connection with contact R1B
The first relay F1 is connected to the first relay F1 so as to be energized. (5) B contact F1B of first relay F1 and third relay R1
Series connection with the B contact R1B of the second relay N1 (6) B contact F1B of the first relay F1 and the second relay N1
Series connection of the B contact N1B of the third relay R1 and the A contact of the third relay R1, the fifth relay R2, and the B contact F1 of the first relay F1.
B and the B contact N1B of the second relay N1 and the A contact R1A of the third relay R1 are connected in series so as to energize the third relay R1 via the diode 18. (7) A contact F2A of fourth relay F2 and forward solenoid 23 (8) A contact R2A of fifth relay R2 and reverse solenoid 25

In each of the relays in FIG. 2, a circle mark indicates a normally open contact that is OFF when the corresponding relay is demagnetized, and is turned on when the corresponding relay is excited, and a ● mark indicates that the corresponding relay is demagnetized. It indicates a normally closed contact that is ON when turned ON and turned OFF when the corresponding relay is excited. That is, when a current flows through the first relay F1, the contact F1A is turned on and F1B is turned on.
Is turned off, and when a current flows through the fourth relay F2, the contact F
2A is closed and the forward solenoid 23 is excited.

Next, the operation relating to a typical operation will be described with reference to FIGS. In FIG. 2, when the main switch 7 is turned on, the second relay N1 is excited and the contact N
Since 1B is turned off and both the fourth relay F2 and the fifth relay R2 are demagnetized, the contacts F2A, R2A
Is turned off, the forward solenoid 23 and the reverse solenoid 25 are demagnetized, and the work vehicle is in a neutral state.

When moving forward from this neutral state, when the push button switch 2 for forward operation is pushed as shown in FIG. 3, the first relay F1 is excited and the contact F1A is turned on and F1.
B is turned off. Therefore, the fourth relay F2 is excited, the excitation of the first relay F1 is self-maintained, and the second relay N1 is demagnetized. Therefore, contact F
2A is turned on, the forward solenoid 23 is excited, the output shaft 16 rotates forward, and the forward operation push button switch 2
Even if the hand is released from, since the excitation of the first relay F1 is self-maintained, the control circuit becomes as shown in FIG. 4, the forward solenoid 23 maintains the excited state, and the output shaft 16 continues the forward rotation. The description of the backward movement is omitted because it is the same as that of the forward movement.

When the neutral operation push button switch 3 is pushed in the forward drive state, a control circuit as shown in FIG. 5 is formed, the second relay N1 is excited, and the contact N1A is turned ON or N.
1B is turned off, and the first relay F1 and the fourth relay F2 are turned off. Therefore, since the forward solenoid 23 is demagnetized, the forward rotation of the output shaft 16 is stopped. Even when the neutral operation push button switch 3 is pressed in the reverse drive state, the reverse drive solenoid 25 is demagnetized as in the forward drive state, and the reverse drive rotation of the output shaft 16 is stopped.

When the forward operation push button switch 2 and the reverse operation push button switch 4 are pressed simultaneously, the control circuit shown in FIG. 6 is obtained. That is, when the first relay F1 is excited, the contact F of the series circuit of the fifth relay R2 is
When 1B is opened and excited by the third relay R1, the contact R1B of the series circuit of the fourth relay F2 is opened. Therefore, the fourth
Since both the relay F2 and the fifth relay R2 are demagnetized, both the forward solenoid 23 and the reverse solenoid 25 are not excited and the output shaft 16 is in the neutral state and does not rotate. That is, when the push button switch 2 for forward operation and the push button switch 4 for reverse operation are pressed at the same time, neither forward nor reverse is entered, and the neutral state is established, and the interlock function is exerted to ensure safety. . Similarly, when two or more other switches are simultaneously pressed, the interlock function is exerted and the neutral state is achieved. However, when the forward operation push button switch 2 and the reverse operation push button switch 4 are simultaneously pressed. Since it is the same as, the detailed description is omitted. When the main switch 7 is turned off, the state shown in FIG. 2 is obtained. When the main switch 7 is turned on again, the control circuit 5 is reset and returns to the neutral state as described above.

FIG. 7 is a circuit diagram of a forward / reverse switching control circuit showing a second embodiment of the control device 5, and a main switch 7
And the battery 8 form a power supply circuit. The forward / reverse switching device for the work vehicle receives the signals from the respective push button switches, and the forward / reverse clutches 12, 13 of the work vehicle are received.
Is provided with a control circuit for exciting the solenoids 23, 25 of the solenoid valves 22, 23 for feeding oil to a cylinder (not shown), and the push button switches 2, 3 are provided between both terminals of the control power supply 8 in the control circuit. , 4, relays F1, N
1, R1, relay contacts F1A, F1B, F2A, N1
B, R1A, R1B, R2A or diodes 17, 1
8 are connected in series as shown below. (1) Push button switch 2 for forward operation and first relay F
1 (2) Pushbutton switch 3 for neutral operation and second relay N
1 (3) Push-button switch 4 for reverse operation and third relay R
1 (4) A contact F1A of the first relay F1 and the second relay N
1 B contact N1B and B contact R1B of the third relay R1 are connected in series, the forward solenoid 23, and the first relay F.
The first A-contact F1A, the B-contact N1B of the second relay N1, and the B-contact R1B of the third relay R1 are connected in series so as to energize the first relay F1 via the diode 17. (5) B contact F1B of first relay F1 and third relay R1
Series connection with the B contact R1B of the second relay N1 (6) B contact F1B of the first relay F1 and the second relay N1
Series connection of the B contact N1B of A and the A contact of the third relay R1 and the reverse solenoid 25, and the B contact F1B of the first relay F1, the B contact N1B of the second relay N1, and the third relay R.
The third relay R1 is connected so as to be energized through the diode 18 from the series connection with the first A contact R1A.

The operation of the contacts marked with a circle and a circle in FIG. 7 and the operation relating to the typical operation of FIG. 7 are the same as those in FIGS.

[0023]

Since the present invention is configured as described above,
The following effects are achieved. (1) The momentary type push-button switch facilitates operation, and the operator can operate the work machine with the right hand, and the left hand can simultaneously perform the steering operation and the forward / backward operation. improves. (2) The push button switch is operated once, and the self-holding function holds the output even if the button is released, which facilitates the operation. (3) Even if two or more push button switches are operated at the same time, it is safe because the interlock function works to make it neutral. (4) When the control circuit is reset, the control circuit returns to the neutral state, which improves safety.

[Brief description of drawings]

FIG. 1 is an overall control circuit diagram of a forward / reverse switching device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a forward / reverse switching control circuit of the first embodiment shown in FIG.

FIG. 3 is a circuit diagram when a main switch and a forward operation push button switch are turned on in FIG.

FIG. 4 is a circuit diagram showing the self-holding state of FIG.

FIG. 5 is a circuit diagram after the neutral operation push button switch is turned on in the state of FIG. 4;

FIG. 6 is a diagram showing a state in which after turning on the main switch in FIG.
FIG. 7 is a circuit diagram showing a state after the forward operation push button switch and the reverse operation push button switch are turned on at the same time.

FIG. 7 is a circuit diagram of a forward / reverse switching control circuit according to a second embodiment of FIG.

FIG. 8 is a layout view of a driver's seat in the first conventional technique.

FIG. 9 is an external perspective view of a steering lever according to a second conventional technique.

FIG. 10 is a front view of a steering lever according to a third conventional technique.

[Explanation of symbols]

1 ... Steering monolever, 2 ... Push button switch for forward operation, 3 ... Push button switch for neutral operation, 4 ... Push button switch for reverse operation, 5 ... Control Device, 7 ... Main switch, 12 ... Forward clutch,
13 ... Reverse clutch, 22 ... Forward solenoid valve, 23 ... Forward solenoid, 24 ... Reverse solenoid valve, 25 ... Reverse solenoid

Claims (3)

[Claims] 1. A work vehicle having a steering lever provided with a forward-reverse switching switch for traveling, wherein the steering lever is provided with respective push button switches capable of switching at least three positions of forward, neutral and reverse. Forward / reverse switching device for working vehicles. 2. The control circuit according to claim 1, further comprising a control circuit for energizing a solenoid valve for receiving oil from each of the push button switches and feeding oil to each of the forward and backward clutches of the work vehicle. A forward / reverse switching device for a work vehicle, characterized in that a push button switch, a relay, a relay contact or a diode is connected between both terminals of the work vehicle as follows. (1) Connect the forward operation push button switch and the first relay (F1) in series. (2) The pushbutton switch for neutral operation and the second relay (N1) are connected in series. (3) Connect the reverse operation push button switch and the third relay (R1) in series. (4) The A contact of the first relay (F1) and the second relay (N
1) The B contact and the B contact of the third relay (R1) are connected in series, and the A contact of the first relay (F1) and the second relay (N) are connected in series.
The B contact of 1) and the B contact of the third relay (R1) are connected in series so as to energize the first relay (F1) through the diode. (5) The B contact of the first relay (F1) and the third relay (R
1) The series connection with the B contact and the second relay (N1) are connected in series. (6) The B contact of the first relay (F1) and the second relay (N
The B contact of 1) and the A contact of the third relay (R1) are connected in series, and the fifth relay (R2) is connected in series, and the B contact of the first relay (F1) and the second relay are connected. (N
The B contact of 1) and the A contact of the third relay (R1) are connected in series so as to energize the third relay (R1) through the diode. (7) The A contact of the fourth relay (F2) and the forward solenoid are connected in series. (8) Connect the A contact of the fifth relay (R2) and the reverse solenoid in series. 3. The control circuit according to claim 1, further comprising a control circuit for exciting a solenoid valve for receiving oil from each push button switch and feeding oil to each of the forward and backward clutches of the work vehicle. A forward / reverse switching device for a work vehicle, characterized in that a push button switch, a relay, a relay contact or a diode is connected between both terminals of the work vehicle as follows. (1) Connect the forward operation push button switch and the first relay (F1) in series. (2) The pushbutton switch for neutral operation and the second relay (N1) are connected in series. (3) Connect the reverse operation push button switch and the third relay (R1) in series. (4) The A contact of the first relay (F1) and the second relay (N
1) The B contact and the B contact of the third relay (R1) are connected in series, and the forward solenoid is connected in series, and
In order to energize the first relay (F1) through the diode from the series connection of the A contact of the first relay (F1), the B contact of the second relay (N1), and the B contact of the third relay (R1) In series. (5) The B contact of the first relay (F1) and the third relay (R
1) The series connection with the B contact and the second relay (N1) are connected in series. (6) The B contact of the first relay (F1) and the second relay (N
In addition to connecting the B contact of 1) and the A contact of the third relay (R1) in series, and the reverse solenoid in series,
From the series connection of the B contact of the first relay (F1), the B contact of the second relay (N1), and the A contact of the third relay (R1), the third relay (R1) is energized via the diode. In series.